Yes I'm aware of that use case but I'm wondering if we can keep things simpler, both for us and users (there are benefits about not having to know about more annotations).

So for example, having your example in mind, it wouldn't be hard for the user to add an additional, ad-hoc transient field having a lower precision type. Not suggesting that this issue is invalid, but wondering if we can agree that it's low priority: I'd rather move it to 5.x or even 6